Multi-directional rod reducer instrument and method

ABSTRACT

A surgical reducing instrument is used to position an elongated implant element in a desired position relative to one or more of the bone anchors of a spinal implant system. The reducing instrument includes a mounting member that is mounted to the anchor and extends along a first longitudinal axis and an implant reducing member pivotally linked to the mounting member that extends along a second longitudinal axis that is offset from and variably positionable relative to the first longitudinal axis about a pivot axis. The reducing member contacts the implant element and includes a manipulation portion to move the implant element along the second longitudinal axis and can maintain contact to move the implant element toward the bone anchor when the reducing member is pivoted relative to the mounting member about the pivot axis.

BACKGROUND

The present application relates to a surgical instrument and a manner ofusing the same, and more particularly, but not exclusively, relates tothe reduction of spinal rods or other elongated implant components toone or more bone anchors in an orthopedic construct for treatment of aspinal deformity.

The use of surgical instruments to place components in orthopedicconstructs has become commonplace. In particular, spinal implant systemsfrequently include several bone anchors and an interconnecting rod thatis shaped to provide a desired spinal curvature. Typically, the boneanchors are implanted first and the rod is then fixed to the boneanchors in succession. As this procedure progresses, some degree offorce may need to be applied to reduce the distance between the rod andthe next anchor to be connected to it. Accordingly, various instrumentshave been described to facilitate such rod reduction. In this arena, thedesire persists for better rod reducing capability. Thus, there is aneed for additional contributions in this area of technology.

SUMMARY

One embodiment of the present application is a unique surgicalinstrument. Other embodiments include unique methods, systems, devices,instrumentation, kits, and apparatus involving an implant reductioninstrument.

According to one aspect, a surgical reducing instrument is used toposition an elongated implant element in a desired position relative toone or more of the bone anchors of a spinal implant system. The reducinginstrument includes a mounting member that is mounted to the anchor andextends along a first longitudinal axis and an implant reducing memberpivotally linked to the mounting member that extends along a secondlongitudinal axis that is offset from and variably positionable relativeto the first longitudinal axis about a pivot axis. The reducing membercontacts the implant element and includes a manipulation portion to movethe implant element along the second longitudinal axis and can maintaincontact to move the implant element toward the bone anchor when thereducing member is pivoted relative to the mounting member about thepivot axis.

According to another aspect, a surgical instrument to position animplant element relative to a bone anchor of a spinal implant systemincludes an elongated extension, a mounting member, a reducing memberand a lateral displacement member. The extension includes a distal endremovably engageable to the bone anchor and extends along a firstlongitudinal axis from the anchor a proximal end. The mounting member isremovably mountable to the proximal end of the extension along the firstlongitudinal axis. The reducing member extends along a secondlongitudinal axis and is pivotally linked about a pivot axis to themounting member in side-by-side relation therewith. The reducing memberincludes at least one leg movable distally along the second longitudinalaxis for positioning in contact with the implant element. The lateraldisplacement member is engaged to one of the mounting member and thereducing member and is positionable in contact with a proximal portionof the other of the mounting member and the reducing member. The lateraldisplacement member is operable to move the proximal portion of thereducing member away from the mounting member about the pivot axis tomove a distal end of the at least one leg toward the distal end of theextension and thus position the implant element in a location moreproximate the bone anchor.

In another aspect, a surgical instrument is operable to positionimplants relative to a bone anchor of a spinal implant system. Theinstrument includes an elongated implant element, a mounting memberremovably mountable to the bone anchor along a first longitudinal axis,and a reducing member. The mounting member includes at least one linkingarm extending therefrom in an oblique orientation to the firstlongitudinal axis to a pivot end. The reducing member extends along asecond longitudinal axis and includes a housing portion and amanipulation portion mounted to and movable relative to the housingportion. The housing portion is pivotally coupled to the pivot end ofthe linking arm about a pivot axis. The manipulation portion includes atleast one distally extending leg contacting the implant element. The atleast one leg is movable distally relative to the housing portion alongthe second longitudinal axis for moving the implant element along thesecond longitudinal axis and the reducing member is pivotal relative tothe mounting member about the pivot axis to change an orientation of thefirst and second longitudinal axes relative to one another and move theimplant element transversely to the first longitudinal axis.

According to another aspect, a method for positioning an implant elementinto a bone anchor, comprises: engaging the bone anchor to a vertebra ofa spinal column; positioning the implant element adjacent the boneanchor; mounting a mounting member to the bone anchor with the mountingmember extending proximally from the bone anchor along a firstlongitudinal axis; contacting the implant element with a reducingmember, the reducing member being pivotally linked to the mountingmember about a pivot axis and extending along a second longitudinal axisin generally side-by-side relation with the first longitudinal axis;distally displacing the implant element relative to the bone anchor bymoving at least one portion of the reducing member along the secondlongitudinal axis; and laterally displacing the implant element towardthe bone anchor by pivoting the reducing member about the pivot axistoward the bone anchor while maintaining contact with the implantelement.

Further embodiments, forms, features, aspects, benefits, objects, andadvantages of the present application shall become apparent from thedetailed description and figures provided herewith.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a posterior elevation view of a spinal column segment andspinal implant system.

FIG. 2 is a perspective view of one embodiment surgical reductioninstrument for positioning an implant element in a desired positionrelative to an anchor.

FIG. 3 is a top plan view of the surgical reduction instrument of FIG.2.

FIG. 4 is a side plan view of the surgical reduction instrument of FIG.2.

FIG. 5 is a perspective view showing an assembly including the surgicalinstrument of FIG. 2 mounted to an extension extending from an anchorand further with the surgical instrument engaged to an implant.

FIG. 6 is an elevation view of the assembly of FIG. 5 showing reductionof the implant element toward the bone anchor.

FIG. 7 is a side view showing the assembly and the implant elementreduced into the bone anchor and a driving instrument positioned tosecure the implant element in the bone anchor.

FIG. 8 is a side view looking in the direction opposite the direction ofFIG. 7 showing the implant element reduced into the bone anchor and thedriving instrument positioned to secure the implant element in the boneanchor.

DETAILED DESCRIPTION OF REPRESENTATIVE EMBODIMENTS

For the purpose of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended. Any alterations and further modificationsin the described embodiments, and any further applications of theprinciples of the invention as described herein are contemplated aswould normally occur to one skilled in the art to which the inventionrelates.

FIG. 1 illustrates a posterior spinal implant system 100 located along aspinal column of a patient. More specifically, implant system 100 can beaffixed to bones B of the spinal column segment 102 from a posteriorapproach. Bones B include the sacrum S and several vertebrae V. Implantsystem 100 generally includes several bone anchors 104 and elongatedimplant elements 106 structured to selectively interconnect with boneanchors 104. Implant elements 106 may be a spinal rod, plate, bar, orother elongated element having a length to extend between at least twovertebrae. Implant element 106 may be solid or hollow along some or allof its length and/or may be of homogenous or heterogeneous composition.In implant system 100, bone anchors 104 are affixed to various locationsof the spinal column 102 and interconnected with implant elements 106.Spinal implant system 100 may be used for, but is not limited to,treatment of degenerative spondylolisthesis, fracture, dislocation,scoliosis, kyphosis, spinal tumor, and/or a failed previous fusion.

A surgical reducing instrument 10 used to position implant element 106in a desired position relative to one or more of the bone anchors 104 ofspinal implant system 100 is shown in FIGS. 2-4. Reducing instrument 10includes a mounting member 20 that extends along a first longitudinalaxis 12 and an implant reducing member 50 that extends along a secondlongitudinal axis 14 that is offset from and variably positionablerelative to longitudinal axis 12. Longitudinal axes 12 and 14 can bearranged relative to one another so that each lies in a single planeextending between axes 12 and 14, although such an arrangement is notrequired.

As further shown in FIGS. 5-8, mounting member 20 can be mounted to anextension 130 extending proximally from bone anchor 104 along firstlongitudinal axis 12, and implant reducing member 50 can be engaged toan implant element 106 that is offset from bone anchor 104. Implantreducing member 50 includes at least a portion that is movable relativeto bone anchor 104 along longitudinal axis 14 to move implant element106 distally relative to bone anchor 104 to align implant element 106with bone anchor 104. Implant reducing member 50 is further movablerelative to bone anchor 104 and mounting member 20 about a pivot axis 16to orient second longitudinal axis 14 in the position indicated by axis14′ and in an oblique orientation to first longitudinal axis 12. Suchmovement of reducing member 50 moves implant element 106 along an arc ortransverse path 18 that is transverse to first longitudinal axis 12 andinto a receiver of bone anchor 104 where implant element 106 may besecured therein.

Referring back to FIGS. 2-4, reducing instrument 10 will be discussed infurther detail. Mounting member 20 includes a head portion 22 along aproximal end thereof and an extension 24 extending distally from headportion 22 along longitudinal axis 12. Mounting member 20 includes acentral passage 32 extending distally and proximally through headportion 22 and extension 24 along first longitudinal axis 12. At least aportion of central passage 32 can be sized for positioning about aproximal end of extension 130 to locate reducing instrument 10 inposition relative to bone anchor 104. Extension 24 can further include aradial flange to facilitate grasping and manipulation of mounting member20 and extension 24.

Mounting member 20 is linked to reducing member 50 with a pair oflinking arms 26 that extend distally from head portion 22 and arepivotally coupled to opposite sides of a housing portion 52 of reducingmember 50 with mounting anchors 28. Linking arms 26 can extend in anoblique orientation to longitudinal axis 12, as shown more clearly inFIG. 6, so that reducing member 50 and mounting member 20 can beoriented with axes 12 and 14 in offset and parallel relation to oneanother. Linking arms 26 can be integrally formed with head portion 22.

Reducing member 50 includes a housing portion 52 having a box-like andelongated configuration along longitudinal axis 14. Linking arms 26 arepivotally coupled to opposite sides of housing portion 52. Housingportion 52 includes an internal cavity 53 having a proximal opening 55in communication with cavity 53. Housing portion 52 further includes apair of rails 68 extending along a distal portion thereof that define adistally opening slot 74 therebetween that is in communication withcavity 53. Rails 68 further include windows 72 extending therethrough incommunication with cavity 53. Rails 68 also include grooves 70 extendingalong at least distal portions thereof. Grooves 70 are formed along therespective inner sides of rails 68 and are oriented so that they arefacing one another.

Reducing member 50 further includes a manipulation portion 80 engagedwith housing portion 52 and movable relative thereto to guide implantelement 106 in contact therewith toward bone anchor 104. Manipulationportion 80 includes an elongated drive member 62 extending alonglongitudinal axis 14 with a shaft 64 extending between a distalconnector 60 and a proximal handle 66. Shaft 64 can include an outerthread profile extending therealong within housing portion 52. First andsecond legs 54 extend distally from the U-shaped connector 60 alonglongitudinal axis 14 to respective distal ends 56. Distal ends 56 eachinclude a distally oriented concave engaging surface 58 configured toextend at least partially about the implant element 106 to couple orcontact implant element 106 with manipulation portion 80. Engagingsurfaces 58 are oriented to extend toward bone anchor 104 so that anelongated implant element 106 can be positioned to extend between legs54 transversely to longitudinal axis 14.

Legs 54 can be separated from one another by a space to allow at leastthe distal ends 56 of legs 54 to be received on opposite sides of boneanchor 104 and facilitate positioning of implant element 106 into boneanchor 104 by manipulating the location of legs 54 relative to boneanchor 104. Legs 54 can be rigidly connected together with connector 60to facilitate application of manipulation forces through the legs 54 tothe implant element 106 in contact therewith. In addition, legs 54 canbe received in respective ones of the grooves 70 along rails 68 toprovide further stability to legs 54 as implant manipulation forces areapplied through legs 54 to implant 106.

Shaft 64 extends proximally from housing portion 52 to handle 66. Handle66 can be a T-handle transversely oriented to shaft 64, although otherhandle configurations are contemplated. Handle 66 can be permanentlyaffixed or removable from shaft 64. Other embodiments contemplate thatshaft 64 can include a proximal end configured to engage a mechanicaldrive instrument. Shaft 64 can include a radially extending flange 65proximal of housing portion 52 that contacts the proximal end of housingportion 52 about proximal opening 55 to limit distal displacement ofmanipulation portion 80 relative to housing portion 52. The distal endof shaft 64 is captured in connector 60 and rotatable relative theretoso that rotation and distal advancement of shaft 64 translates intoaxial and non-rotational distal displacement of legs 54 along rails 68.

In one embodiment, reducing member 50 can further include aquick-release mechanism 78 mounted to housing portion 52 that isnormally biased into engagement with manipulation portion 80.Specifically, shaft 64 can be threadingly engaged to a retaining member(not shown) in housing portion 52 that is coupled with button portion 79protruding from housing portion 52. Button portion 79 can be normallybiased to protrude from housing portion 52 and so that the retainingmember is normally engaged with shaft 64. When button 79 is depressedinto housing portion 52, the retaining member releases shaft 64 so thatmanipulation portion 80 is free to slide proximally and distally alonglongitudinal axis 14 relative to housing portion 52. In this embodiment,the user has the option to quickly distally displace manipulationportion 80 relative to housing portion 52 without rotating shaft 64 withhandle 66. In other embodiments, a quick-release mechanism is notprovided and shaft 64 is threadingly engaged to housing portion 52, suchas within proximal opening 55.

In order to facilitate and provide a mechanical advantage in movingreducing member 50 about pivot axis 16, and thus in moving implantelement 106 along an arc defined by a radius extending through pivotaxis 16, a lateral displacement member 40 is provided. Lateraldisplacement member 40 includes an elongated shaft 46 extending alonglongitudinal axis 42 to an outer handle 44. Longitudinal axis 42 can beobliquely oriented to a plane 17 including first and second longitudinalaxes 12 and 14 (FIG. 3) so that lateral displacement member 40 does notobstruct passage 32. Handle 44 can be a T-handle transversely orientedto shaft 46, although other handle configurations are contemplated.Handle 44 can be permanently affixed or removable from shaft 46. Otherembodiments contemplate that shaft 46 can include an outer endconfigured to engage a mechanical drive instrument.

Shaft 46 includes a contact end 48 opposite handle 44 that is positionedin contact with an outer surface of housing portion 52 adjacent theproximal end of housing portion 52 proximally of pivot axis 16. Shaft 46is threadingly engaged through a bore 30 in proximal head portion 22 ofmounting member 20 that extends along axis 42. Contact end 48 is movablealong axis 42 in the direction of arrow 43 (FIG. 6) into contact withthe proximal portion of housing portion 52, and is further movable alongaxis 42 to pivot reducing member 50 about pivot axis 16. This in turnmoves implant element 106 along an arc or path 18 toward bone anchor104. Reducing member 50 can be pivoted about axis 16 in the oppositedirection when contact end 48 is displaced from the proximal portionthereof by threading shaft 46 in bore 30 in the opposite direction ofarrow 43 along axis 42.

In another embodiment, lateral displacement member 40 can be mounted toreducing member 50 by, for example, shaft 46 threadingly engaging a borein the proximal portion of reducing member 50. Contact end 48 cancontact a proximal end of mounting member 20, and is operable byrotation of shaft 46 to displace the reducing member 50 about pivot axis16.

Referring now to FIGS. 5-8, a method employing reducing instrument 10will be discussed. Bone anchor 104 is shown removed from engagement witha bone structure, it being understood that bone anchor 104 could beengaged to any portion of any vertebra of a spinal column including thesacral, lumbar, cervical and/or thoracic regions. Elongate implantelement 106 is provided with a length positionable between at least twovertebrae, and is shown adjacent to but spaced from bone anchor 104.Implant element 106 can be engaged to one or more other bone anchorsprior to engagement with bone anchor 104. The anatomical structures andimprecise alignment between multiple bone anchors 104 can makepositioning implant element into each of the bone anchors 104 difficult,particularly if implant element 106 includes a rigid or semi-rigidstructure.

In the illustrated embodiment, bone anchor 104 is a side-loading typebone anchor with a distal bone engaging shaft 110 in the form a bonescrew and a proximal head 112 defining a passageway 114 for receivingimplant element 106 therethrough. The proximal head 112 can include aset screw or other suitable device for securing implant element 106 inthe passageway 114 after it is positioned therein. Passageway 114 canopen in the direction toward longitudinal axis 14 so that implantelement 106 can be positioned therein when moved along lateral path 18.

Bone anchor 104 can further include a removable and proximally extendingextension 130 extending from head 112. Extension 130 can include anelongated body 132 with a distal engaging end 134 removably andclampingly engaged to head portion 112 of bone anchor 104. Body 132 canalso include a proximal end 136 sized to receive mounting member 20thereover in sliding and removable engagement therewith. Mounting member20 can be axially secured to extension 130 with any suitable means,including one or more set screws, clamping members, threaded interfaces,bayonet or twist locks, for example.

In one embodiment, extension 24 can include a quick disconnect typemechanism that axially secures mounting member 20 to extension 130. Forexample, extension 24 can include an inner sleeve and an outer sleeveaxially biased relative to one another, and a number of ball membersbetween the sleeves biased radially inwardly toward passage 32 whencontacted by the outer sleeve but retained between the sleeves by theinner sleeve. The ball members can be unlocked by lifting the outersleeve relative to the inner sleeve to axially displace the sleevesrelative to one another, aligning a receptacle in the outer sleeverelative to the ball members so that the ball members can move away frompassage 32 when contacted by an object in passage 32. Proximal end 136is then free to slide into passage 32 to the desired depth withoutinterference from the ball members. The outer sleeve can then bereleased to return to its normally biased position, contacting the ballmembers and forcing the ball members into passage 32 and into contactwith proximal end 136 of extension 130 to provide an axially secureengagement relationship therewith. Proximal end 136 can include aflange, receptacle or other structure to provide positive axialengagement with the ball members or retained by a friction fit.

In any embodiment, extension 130 can be secured to bone anchor 104 priorto attachment of mounting member 20 to extension 130. Alternatively,mounting member 20 can be secured first to the extension 130, and theinstrument assembly mounted to the bone anchor 104 as shown in FIG. 5.

Lateral displacement member 40 is situated relative to reducing member50 so that reducing member 50 can freely pivot about axis 16 to alignlegs 54 with implant element 106. Once aligned, manipulation portion 80can be distally displaced by rotating shaft 64 with handle 66, movinglegs 54 distally along rails 68 until contact with implant element 106is attained. Alternatively, push button 79 can be depressed to disengagequick-release mechanism 78 from shaft 64 so that manipulation portion 80can axially and distally slide or translate relative to housing portion52 into contact with implant element 106. Once contact with implantelement 106 is achieved, button 79 is released and shaft 64 isre-engaged to allow displacement of shaft 64 and legs 54 by rotation ofhandle 66.

Manipulation portion 80 can then be axially displaced while in contactwith implant element 106, if necessary, to distally displace implantelement 106 along axis 14 as indicated by arrow 15 in FIG. 6. Onceimplant element 106 is aligned or nearly aligned with the side openinginto passageway 114 of head portion 112, lateral displacement member 40is manipulated with handle 44 to position contact end 48 in contact withhousing portion 52 and rotate reducing member 50 about pivot axis 16.This in turn displaces implant element 106 along path 18 toward headportion 112. If implant element 106 is not aligned sufficiently distallyor proximally with the opening into passageway 114, handle 66 can berotated to distally or proximally displace manipulation portion 80 toprovide fine tuning of the location of implant element 106 relative topassageway 114. When the desired alignment is achieved, lateraldisplacement member 40 can be further operated to position and seatimplant element 106 in passageway 114 as shown in FIGS. 7 and 8.

When implant element 106 is seated in head portion 112, legs 54 arepositioned on opposite sides of head portion 112 and maintain implantelement 106 in position through the engagement of lateral displacementmember 40 with housing portion 52 and engagement of drive member 62 tohousing portion 52. A driver instrument 140 can be positioned throughpassage 32 and through an internal passage of extension 130 to engage aset screw or other locking device on head portion 112. Driver instrument140 can be rotated to rotate the locking device and finally engageimplant element 106 in head portion 112. Reducing instrument 10 can thenbe removed by either disengaging extension 130 from bone anchor 104, orby disengaging mounting member 20 from extensions 130. The procedure canbe repeated at various anchor locations if necessary or desirable tosecure implant element 106 or another implant element to one or moreother anchors along the spinal column.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be consideredillustrative and not restrictive in character, it being understood thatonly selected embodiments have been shown and described and that allchanges, equivalents, and modifications that come within the scope ofthe inventions described herein or defined by the following claims aredesired to be protected. Further, when the language “at least a portion”and/or “a portion” is used, the claims may include a portion and/or theentire item unless specifically stated to the contrary.

1. A surgical instrument to position an implant element relative to abone anchor of a spinal implant system, comprising: an elongatedextension with a distal end removably engageable to the bone anchor andextending along a first longitudinal axis from said distal end to aproximal end; a mounting member removably mountable to said proximal endof said extension along said first longitudinal axis, wherein saidmounting member includes first and second linking arms extendingdistally from a proximal end of said mounting member; a reducing memberextending along a second longitudinal axis, said reducing member beingpivotally linked to said mounting member in side-by-side relation abouta pivot axis, said reducing member including at least one leg movabledistally along said second longitudinal axis for positioning in contactwith the implant element, wherein said first and second linking armsinclude distal ends coupled to opposite sides of said reducing member atsaid pivot axis and said first and second linking arms extend proximallyfrom said distal ends in an oblique orientation to said first and secondlongitudinal axes to said proximal end of said mounting member when saidfirst and second longitudinal axes are positioned in parallel relationto one another; and a lateral displacement member engaged to one of saidmounting member and said reducing member and having a spaced positionfrom a proximal portion of the other of said mounting member and saidreducing member, said lateral displacement member being movable fromsaid spaced position into contact with said proximal portion of saidother of said mounting member and said reducing member while engaged tosaid one of said mounting member and said reducing member to move saidproximal portion of said reducing member away from said mounting memberabout said pivot axis and to move a distal end of said at least one legtoward said distal end of said extension thereby positioning the implantelement in a location more proximate the bone anchor.
 2. The instrumentof claim 1, wherein said mounting member includes a proximal headportion and a cylindrical extension extending distally from said headportion, said head portion and said extension defining a passagetherethrough along said first longitudinal axis.
 3. The instrument ofclaim 2, wherein said head portion includes a bore extendingtherethrough transversely to said first longitudinal axis, and saidlateral displacement member extends through said bore in threadedengagement with said mounting member therein.
 4. The instrument of claim3, wherein said lateral displacement member includes a first endpositionable in contact with said reducing member and an opposite endincluding a handle, said lateral displacement member further includingan elongated shaft extending between said first end and said handle. 5.The instrument of claim 4, wherein said bore extends along a third axisthat is obliquely oriented to a plane that is defined by said first andsecond longitudinal axes.
 6. The instrument of claim 1, wherein saidreducing member includes: an elongated housing portion including a bodydefining a cavity along said second longitudinal axis; and amanipulation portion extending through said housing portion, saidmanipulation portion including a handle proximal of said housing and apair of legs extending distally from said housing portion for contactwith the implant element.
 7. The instrument of claim 6, furthercomprising an elongated shaft between said handle and said pair of legs,wherein said pair of legs are joined at proximal ends thereof with aconnector and a distal end of said shaft is rotatably engaged to saidconnector.
 8. The instrument of claim 7, wherein said elongated shaftincludes an external thread profile and is threadingly engaged to saidhousing portion, wherein rotation of said elongated shaft with saidhandle axially and rotationally displaces said shaft along said secondlongitudinal axis, which in turn axially and linearly displaces saidpair of legs along said second longitudinal axis.
 9. The instrument ofclaim 6, wherein said pair of legs each include a distal end with aconcavely curved distal end surface for contacting the implant elementwhen the implant element is positioned between the pair of legs.
 10. Theinstrument of claim 6, wherein said housing portion includes a pair ofrails extending distally therealong and said pair of legs are slidablyreceived in grooves along facing sides of said pair of rails.
 11. Asurgical instrument to position implants relative to a bone anchor of aspinal implant system, comprising: an elongated implant element; amounting member removably mountable to the bone anchor along a firstlongitudinal axis, said mounting member including at least one linkingarm extending therefrom to a pivot end in an oblique orientation to saidfirst longitudinal axis; a reducing member extending along a secondlongitudinal axis adjacent said mounting member, said reducing memberincluding a housing portion and a manipulation portion mounted to andmovable relative to said housing portion, said housing portion beingpivotally coupled to said pivot end of said linking arm about a pivotaxis with said at least one linking arm obliquely oriented to saidsecond longitudinal axis and with said at least one linking armextending in a proximal direction away from the bone anchor to aproximal end of said mounting member, and said manipulation portionincludes at least one distally extending leg contacting said implantelement, wherein said at least one leg is movable distally relative tosaid housing portion along said second longitudinal axis for moving saidimplant element along said second longitudinal axis and said reducingmember is pivotal relative to said mounting member about said pivot axisto change an orientation of said first and second longitudinal axesrelative to one another and move said implant element transversely tosaid first longitudinal axis; and a lateral displacement member engagedto said mounting member, said lateral displacement member having aspaced position from said reducing member, said lateral displacementmember being movable from said spaced position to contact said reducingmember while said lateral displacement member is engaged to saidmounting member to push a proximal end of said reducing member away fromsaid mounting member about said pivot axis and move said implant elementin contact with said distally extending leg toward said firstlongitudinal axis.
 12. The instrument of claim 11, wherein said mountingmember includes a bore extending therethrough transversely to said firstlongitudinal axis, said lateral displacement member extending throughsaid bore and engaging said mounting member therein.
 13. The instrumentof claim 12, wherein said lateral displacement member includes a firstend positionable in contact with said reducing member and an oppositeend including a handle, said lateral displacement member furtherincluding an elongated shaft extending between said first end and saidhandle, said shaft including a thread profile threadingly engaging saidmounting member in said bore.
 14. The instrument of claim 12, whereinsaid bore extends along a third axis that is obliquely oriented to aplane that is defined by said first and second longitudinal axes. 15.The instrument of claim 11, further comprising an elongated extensionwith a distal end removably engageable to the bone anchor and bodyextending along said first longitudinal axis to a proximal end removablyengageable with said mounting member.
 16. The instrument of claim 11,wherein said at least one linking arm includes a pair of linking armspivotally coupled to opposite sides of said housing portion at saidpivot axis.
 17. The instrument of claim 11, wherein said at least oneleg of said manipulation portion includes a pair of legs extending inside-by-side and spaced relation to one another, each of said pair oflegs defining a concavely curved distal end and said implant element ispositioned between said pair of legs in said concavely curved distalends.
 18. The instrument of claim 17, wherein said manipulation portionfurther comprises an elongated shaft between a proximal handle and saidpair of legs, wherein said pair of legs are joined at proximal endsthereof with a connector and a distal end of said shaft is rotatablyengaged to said connector.
 19. The instrument of claim 18, wherein saidelongated shaft includes an external thread profile and is threadinglyengaged to said housing portion between said proximal handle and saiddistal end of said shaft, wherein rotation of said elongated shaft withsaid handle axially and rotationally displaces said shaft along saidsecond longitudinal axis, which in turn axially and linearly displacessaid pair of legs along said second longitudinal axis.
 20. Theinstrument of claim 17, wherein said housing portion includes a pair ofrails extending distally therealong and said pair of legs are slidablyreceived in grooves along facing sides of said pair of rails.